The long-term goal of this project is to isolate and characterize membrane antigens of human leukemia cells. We have elicited a number of monoclonal antibodies to lymphoid and myeloid leukemic cell antigens. We have identified the molecular properties of these antigens, established their hematopoietic and tissue distribution and have evaluated them as reagents for phenotyping leukemias and lymphomas. More recently, they have been used by other investigators to treat autologous marrow to eliminate leukemia cells before engraftment into the patient. Some of the monoclonal antibodies to myeloid leukemia antigens are present on progenitor cells, and the monoclonal antibodies are being used to isolate or enrich for these cells from bone marrow, using flow cytometry. We have also participated in a study of a new isolate of HTLV from a patient seen at Duke University Medical Center and, in addition, have reported on the unusual distribution of the p19 antigen associated with HTLV in thymus, tonsil and some malignant tissues from patients with no evidence of HTLV disease.